My husband and I will be doing the day hike to Machu Picchu in September.
Would you recommend hiking boots/socks or Teva type sandals?
Thanks!

Hiking boots definitely.

I would not recommend any open-toed shoes in Peru. (except maybe Lima) Even in the cities and towns, the streets are cobbled, uneven and may be used by people, vehicles & animals including llamas, mules, horses, chickens,dogs, cats, etc.
The streets are charming and unpredictable. Some are ancient and provide an exciting surface on which to walk.

Although the Quechua people seem to go year round in sandals, I would stick with a closed shoe.

If you plan on hiking Huayna Picchu, definitely wear sturdy hiking boots with good traction. Very slippy and dangerous on the way down--steep climb down on wet slippery narrow stone path.

Day hike to Machu Picchu?? to play safe hiking boots or just a runners will be enought